The present invention relates to a maritime power plant system with processes for producing, storing and consuming regenerative energies whereby the power plant system may comprise an individual power plant or may be a network of power plants, whereby the power plant has a common support structure for the devices producing energy and for the devices carrying out other processes.
For using regenerative energy sources, different methods are known. The well known methods include solar energy conversion by photovoltaic tag cells and by thermal collectors. It is also known to employ mirror systems in combination with a steam generator. Also, devices are known which collect hot air with the aid of foils and guide it into the chimney of a thermal uplift power plant.
The kinetic energy of wind is also often used for producing electricity. The use of ocean waves and ocean thermal energy for powering power plants is known to a lesser extent even though a very large energy source, i.e., the ocean, could potentially be used to great advantage.
In the following, an exemplary account of different concepts for generating power by using regenerative energy and the problems correlated therewith will be given.
Photovoltaic devices for hydrogen production in desert areas have been suggested for the use of hydrogen as an energy source by C. -J. Winter and J. Nitsch, 1986. Such devices are combined with hydrogen production by plants at the coast for producing potable water. For electrolysis, the water is pumped through miles of pipelines with great energy expenditure into the desert areas. The hydrogen and oxygen are then conveyed through pipelines back to the costal areas and then farther to Europe. This concept has the disadvantage that the partial processes of the hydrogen production are separated by many miles, and the required materials are brought together with great transmission losses.
Available fresh water reservoirs in desert areas at great depth (ancient non-refillable fresh water reservoir) provide the last reserves for humankind. These water reservoirs are not connected to the circulation of water within the time frame of human consumption and should therefore not be used for hydrogen production in connection with photovoltaic cells.
Large wind-driven power plants with many rotors have been suggested to be operated on the ocean since the 1930's and are known, for example, from the 40 MW Off-Shore Project of Honnef, 1932, and the Off-Shore Project according to Heronemus in the Gulf of Maine, 1972. This is disclosed in the publication Gro.beta.kraft Wind, Felix von Konig, 1988. These concepts, however, have not been further explored and have never been realized.
However, further developments in some respects have been undertaken. For example, a number of different rotor types has been developed. For example, there are single and multiple vane rotors with horizontal and vertical axes. Concentration systems according to the principal of turbulence coils (BERWIAN) or mantle turbines and quasi mantle turbines (tip-vanes) have been designed in an attempt to increase the efficiency of the wind power plants when using smaller size rotors. There are also promising systems such as the Darieus rotor, Flettner rotor and Savonius rotor with which energy can be produced without being dependent on the wind direction. A very interesting type is the so-called Yen turbulence tower, also called the tornado tower, which is disclosed in Windenergie, Jens-Peter Molly, 1990.
In order to increase the efficiency of individual rotor devices, a plurality of such devices is combined in wind parks. For a minimal spacing between the rotors, large surface areas are still required. The concept of wind parks, however, does not find general acceptance by the public because such wind parks are considered an eyesore. The increasing resistance of citizens is directed toward wind park construction sites consuming large surface areas which, in the subjective opinion of residents not involved with the wind park, destroy the landscape and thus reduce the recreational value of the land.
Accordingly, multi rotor concepts have been reintroduced, for example, evidenced by Tagungsband der 3. Deutschen Windenergie-Konferenz Okt. 1996, P. 427, with the goal to optimize the use of the available surface areas. Multi rotor devices require a large support structure with corresponding support problems in order to be able to follow the wind direction. These problems can be avoided by employing vertical axis rotors which operate independent of the wind direction. However, these devices also require a large space. Because of the minimal energy density of free air currents, in general, a large surface area for such wind-powered power plants is required in order to provide for an economic energy output. Also, large spacing to traffic channels such as railways and interstates, to residential areas and nature preserves must be provided. A further limitation results from the density of domestic flight corridors, which must not be obstructed by very tall building structures that are taller than 200 meters.
Another form of regenerative energy is the wave movement of the ocean. Power plants based on ocean waves as disclosed in Wave Energy, A Design Challenge, R. Shaw, 1982, fall into three categories:
1. Buoy types which use the lifting force of the waves by employing a float and a current convertor and by employing gravity as a return force; PA1 2. Convertor types in which the moved water mass and the thus moved air masses above are used to drive a wind turbine; PA1 3. Convertor types which use the moved water masses for driving a water turbine.
For converting the mechanical energy into electrical energy, in addition to the known generator types it is also possible to use piezoresistive current convertors.
Devices for using the wave energy of the ocean, depending on their technical design, are dependent on the direction of the waves. The direction of the waves correlates with the wind direction so that wave energy devices are therefore adjusted according to the direction of the wind in order to improve efficiency. However, in practice this is very difficult because the devices have a size of a few hundred meters and a required water displacement of a few 10,000 to 100,000 tons, this resulting in great inertia. Not all embodiments can therefore be moveable according to the wind direction. Pilot plants have been built in the North Sea which is, in general, considered a very turbulent ocean, before the coast of Great Britain.
The surface of the earth is covered to approximately 70% ocean. Ocean waters therefore provide the largest continuous solar collector that can be provided on earth. In the vicinity of the equator, a sufficient thermal energy is stored within the surface water of the ocean so that between it and the cold ocean bottom waters a thermal dynamic cycle process can be operated. In Lexikon fur Energietechnik-VDI Verlag, 1994, ocean thermal energy conversion (OTEC) power plants are disclosed. With an extrapolation of the mentioned examples the respective power plants have a water displacement of a few 10,000 tons. The respective dimensions can be within the range of a few 100 meters. Heat exchange of the thermal energy of the surface water at approximately 20.degree. and the cold ocean bottom water of approximately 5.degree. C. coming from a depth of 500 to 1,000 meters is carried out. An estimate can be provided by calculation based on the Carnot cycle and leads to an estimated efficiency of approximately 3%.
For producing electricity from the thermal energy stored within the ocean two technical thermodynamic processes are available in addition to the thermoelectric effect. See Renewable Energy from The Ocean, A Guide to OTEC, W. H. Avery, C. WU, 1994. The technically open cycle process removes from the ocean directly, without intermediate use of further cycle processes with easily vaporizable working means, the thermal energy and supplies it to a turbine generator set. In a technically closed cycle process an intermediate cycle process, for example, by using ammonia, removes the energy and guides it to a turbine with a generator. In addition to these two basic types, there are also mixed embodiments in the technical realization of open and closed cycle processes.
Furthermore, OTEC devices are known, (see Energielexikon, Meyer-Verlag), which condense salt-free water vapor in a condenser and thus provide raw water for desalination potable water production.
Ocean water decellanation is of special importance in the connection with regenerative energies. Since water is the basic ingredient of a hydrogen economy, large amounts of free water are required for producing hydrogen and oxygen. Hydrogen is an ideal storage medium for regenerative energy because it has a high degree of efficiency when converted into any other energy form. For conversion it is possible to use fuel cells which directly produce electrical current from hydrogen and oxygen. Furthermore, the waste energy of such cells can be used for covering heating requirements ("Einsatz von Brennstoffzellen" vom, OTTI-Technologie-Kolleg, Ostbayerisches Technologie Transfer Institute e. V. Regensburg, 1994). Also, fresh water in the near future may become a very important foodstuff and thus maybe one of the most valued commodities of humankind. The world reserves of potable water or fresh water are being reduced at an incredible rate. Fossil fuel-operated power plants require a great amount of water in two ways. On the one hand, great amounts of river water are evaporated by cooling towers and the rivers are thus unnecessarily loaded with thermal energy. Nuclear power plants around rivers also contribute to heating the rivers. Furthermore, large amounts of ground water are pumped from their reservoirs for the purpose of mining brown coal. Some of this water is older than 15,000 years. A further negative impact on water quality results from excessive ranching and farming endeavors which, to a great extent, contribute to pollution of fresh water. The sedimentations in the river beds which generally have a cleaning effect are loaded more and more with pollutants. It is much more difficult to provide the required amount of potable water in areas of population concentration. Deep wells have been plundered and the ground water level has been lowered steadily. In many locations all over the earth where humans are living water is already a scarce commodity. It must be transported by truck and then dispensed. Conflicts in regard to the foodstuff water increase world wide.
These arguments are provided to underscore the importance of sea water desalination in the future.
Desalination of sea water can be performed in different ways. In addition to the thermal desalination, such as distillation methods, the reserve osmosis method is becoming more and more important. Reverse osmosis devices require high pressures in order to reverse the concentration gradient between fresh water and salt water thus countering the osmotic pressure. Fresh water is thus essentially pressed out. In the context of these forces there are power plants which employ the osmotic pressure for energy generation. However, this means that large amount of fresh water and sea water (saltwater) must be provided at one location. However, since fresh water is a raw material that is very precious and at the same time is a foodstuff, this method should not be used.
The following concepts and methods for using regenerative energy are current state of the art.
From German Patent Document 36 22 285 a small power plant for simultaneous use of four natural forces in shallow ocean waters is known. The following forces cooperate:
The lifting force of the waves, the gravity acting on a float, the water current, and the kinetic energy of the wind acting on a rotary shaft. The rotary shaft drives a generator. This device can also be used in a group of more devices of the same kind. Lifting force, gravity, and water flow correspond to the three known types of wave-based power plants. The disclosed device employs the kinetic energy of the wind only in the resistance area in the vicinity of the water surface. However, the energy contained in this area is minimal because of the minimal wind speed so that this device is substantially operated by the force of the waves and the water flow.
In German Patent Document 36 27 130, a continuation-in-part application of Patent 36 22 285, a variant is disclosed which does not improve this aspect of wind energy use and which discloses the pressure of the wind only as an additional energy.
In German Patent Document 25 14 447, a wave and wind energy storage power plant is disclosed which drives by compressed air pumps for generating hydraulic potential energy for the purpose of turning water turbines for electricity generation.
From German Patent Document 43 39 824, a floating wind and wave energy power plant is known which is comprised of a sail rotor, designed similar to a Dutch windmill, and a wave paddle wheel. The energy is transmitted to a common rotating energy storage device. The rotating storage device cooperates with an electric generator in order to produce electric energy.
In German Patent Document 27 52 892, a wind and wave energy device in combination with a tidal power plant is disclosed for generating electricity. Combining different regenerative sources with the tidal energy is possible only at a few locations on this earth because this power plant type requires a tidal lift of at least 3 meters in order to operate properly. For the German North Sea coast an average tidal lift of 2.7 meters has been measured. Economical operation would seem possible only when used as an auxiliary energy to be fed into a common supply network.
From German Patent Document 195 02 953, a mechanical energy generator is known which, for example, suggest the combination of wind energy, water energy, solar energy and biomass energy. An energy storage device is disclosed which collects the different types of energies in the form of rotational energy and this energy is converted by a generator into electric current. This device can be used on land as well as on the ocean. In principle, it is possible to convert basically any type of energy into rotational energy. In order to be able to use this energy, the storage devices with their generators must be operated in the vicinity of the supply network in order to be able to supply the current to the consumer. When connection to a network is not possible, a chemical energy storage must be employed in order to allow transport of energy to the consumer. Furthermore, with rotating masses, which receive a corresponding amount of energy, a complicated service and maintenance system is required and friction will cause a certain amount of loss.
In German Patent Document 38 08 536, a wind-powered device is disclosed which produces fresh water from sea water according to the principle of reverse osmosis without requiring intermediate energy conversion into electric current. The wind energy is directly converted into the pressure required for reverse osmosis.
The following German documents DE 36 34 102, DE 33 32 810, DE 37 04 280, DE 36 22 119, DE 41 37 569, DE 25 20 044, and DE 43 10 843 disclose floating or stationarily secured devices which produce the required amount of electric current for hydrogen production only by wind energy or solar energy. Some of these floating devices can be operated while stationary as well as while being moved.
A method for using thermal and/or mechanical energy potentials, especially with minimal potential differences, is disclosed in German Patent 40 17 684. This reference mentions only that, when using the potential difference, electrical energy is first produced, at the production location, respectively, in its vicinity water is electrically cleaved into oxygen and hydrogen, the hydrogen is used for reducing metal or metal oxide, and the resulting metal hydride is employed where needed together with oxygen by releasing heat energy or is used in fuel cells for producing electrical energy.
This method does not explain in which manner and where the inventive method can be economically and ecologically effectively used.
In summarizing the above the problems when using regenerative energy can be classified as follows.
Due to the minimal energy density of regenerative energy sources relative to conventional fuels, energy convertors for solar radiation and kinetic energy of wind require large surface areas. Convertors for ocean thermal energy and wave energy require large and heavy devices in order circulate the required amount of water and to thus be able to produce in an economical manner electric current and heat energy.
The second problem is the inconsistent supply of energy at the location of energy production over time. For example, the energy cannot be provided in correlation to the consumer demand because the flow of energy occurs only with a statistical distribution and is not always available when requested by the consumer.
It is therefore an object of the present invention to provide a concept that, with a combination of different methods for energy production, provides a continuous energy flow of regenerative energy sources. The produced energy can be stored with universal energy storage devices but can also be directly employed in industrial production processes. This concept is advantageous in that the selected system technology can be used in an advantageous manner because the individual processes, can compliment one another or even dependant on one another, while their disadvantages are overcome, in order to thus provide an efficiency increase with respect to the individual devices.